The present invention relates to a cushioning device for rotatable components, such as, for example, roof grab handles or sun vizors of a vehicle, having an outer rotational sleeve and an inner rotational part, which are both arranged in a manner such that they can rotate relative to each other about a common axis of rotation from a first rotational position into a second rotational position, either the inner rotational part being fixed and the outer rotational sleeve being rotatable or the outer rotational sleeve being fixed and the inner rotational part being rotatable.
Roof grab handles in vehicles are frequently designed as folding handles. Folding handles of this type are folded by hand from the inoperative position, i.e. from a position leaning against the roof lining, into a functional position. When let go, these folding handles automatically pivot back into the inoperative position.
Sun shielding vizors are also designed as foldable components. After a brief actuation by hand, said sun shielding vizors automatically pivot into the functional position. An automatic retracting pivoting movement can also be carried out when folding them back.
Folding handles having a handle strap are known, said strap, if let go in the functional position, striking under the effect of its restoring spring against the bearing bracket or the roof lining and in the process causing annoying noises, or over the course of time damage occurs reducing the functioning ability. Braking devices which damp the restoring movement of the folding handle have therefore been arranged on the folding handles mentioned at the beginning.
EP-A-0 569 022 describes a folding handle which is distinguished in that a braking spring is provided, said spring being arranged to counteract the restoring spring and in the inoperative position precisely compensating for the restoring spring, the inoperative position deviating by a safety angle which is substantially smaller than the handle angle from the end position in which the handle strap strikes against the bearing bracket or the associated installation wall, and the braking spring being effective only in the region of a braking angle between a brake usage position and the end position.
German utility model G 93 14 645.0 shows a pivoting joint primarily for components for vehicles, such as pivoting handles, comprising a bearing sleeve, which are connected in a rotationally fixed manner to a positionally fixed component, for example to a holder, or to a pivotable component, and a bolt which is mounted rotatably in the bearing sleeve and is connected in a rotationally fixed manner to the pivotable component or the positionally fixed component, and a viscosity brake, by means of which a pivoting movement of the parts with respect to one another, which movement is caused by gravitational force or by a spring element, is damped. As the viscosity brake in this case, a circumferential gap which is filled with a medium of high viscosity is formed between the bolt and the bearing sleeve.
German utility model 296 04 260.9 describes a folding handle which is distinguished in that the braking device is designed as a rotational damper and has a radial construction with an, in particular, cylindrical housing, a rotational piston which is sealed with respect to the housing, can be rotated within an annular body and plunges at least in some regions into the annular space filled with viscous medium, the housing has a central, continuous recess, within which the axis of rotation is arranged in some regions, the handle strap or the bolt is connected in a form-fitting manner to the housing of the braking device and the bearing bracket is connected in a form-fitting manner to the rotational piston of the braking unit, or vice versa, and the housing and the rotational piston are clipped together with the aid of a ring and annular groove and said housing and piston form a unit.
Starting from the prior art which has been mentioned, the present invention is based on the technical problem or object of specifying a cushioning device for rotatable components, which device shows a cushioning effect and a braking effect, is constructed from few parts, makes economic production possible and ensures reliable functioning in the long term.
The cushioning device according to the invention is given by the features of independent claim 1. An alternative cushioning device according to the invention is given by the features of independent claim 2. Advantageous refinements and developments are the subject matter of the dependent claims.
Accordingly, a first embodiment of the cushioning device according to the invention is distinguished in that the outer rotational sleeve has, on its inner contour, an inwardly pointing inner stop and the inner rotational part has, on its outer contour, an outwardly pointing counterstop which consists of soft material, reduction of the inner radius of the inner contour of the outer rotational sleeve in the region in front of the inner stop enabling the outer contour of the counterstop to come increasingly more strongly into contact with the inner wall of the outer rotational sleeve during rotation from the first into the second position, as a result of which first of all a braking effect is built up, and, when the counterstop strikes against the inner stop, the soft material of the counterstop enables a cushioning effect to be produced.
Accordingly, a second alternative refinement of the cushioning device according to the invention is distinguished in that the inner rotational part has, on its outer contour, an outwardly pointing counterstop, and the outer rotational sleeve has, on its inner contour, an inwardly pointing inner stop which consists of a soft material, enlargement of the outer radius of the outer contour of the inner rotational part in the region in front of the counterstop enabling the outer contour of the inner stop to come increasingly more strongly into contact with the outer wall of the inner rotational part during rotation from the first into the second position, as a result of which a braking effect is produced, and, when the inner stop strikes against the counterstop, the soft material of the inner stop enables a cushioning effect to be produced.
A braking and a cushioning effect can be reliably produced by the cushioning device according to the invention. The stop noise can be reliably suppressed. The braking effect used in front of the stop means that the components are treated carefully, which ensures reliable functioning in the long term with an increase in the service life of the components.
A further advantage of the cushioning device according to the invention resides in the fact that only two components are required in order to produce the desired, advantageous effects, namely the outer rotational sleeve with its inner stop and the inner rotational part with its counterstop.
An advantageous refinement which ensures economical production is distinguished in that the inner rotational part/the outer rotational sleeve is designed as a two-component plastic part having an injection-molded counterstop/inner stop made of soft material.
According to an advantageous development, the braking and cushioning effect is produced not only during pivoting from the first into the second position, but also the other way around when pivoting from the second position into the first position. This advantageous refinement is distinguished in that there is a further inner stop on the inner contour of the outer rotational sleeve, in the region of which stop the inner radius of the outer rotational sleeve is likewise reduced, with the result that the braking and cushioning effect is produced during rotation from the second position into the first position.
A particularly advantageous refinement of the cushioning device according to the invention is characterized in that on the outer side facing the region in contact with the inner wall of the outer rotational sleeve or the outer wall of the inner rotational part the counterstop/the inner stop has a projecting contour which, during the first contact with the opposite wall, initially produces, as seen in cross section, a point-shaped contact which becomes an extensive contact during further rotation. By virtue of the fact that the projecting contour which is selected enables the counterstop or the inner stop initially only to come into contact in a pointwise manner with the opposite wall and to only come to an extensive contact during further rotation, the braking force is built up more or less continuously.
A particularly preferred development of the cushioning device according to the invention is distinguished in that a retaining projection is integrally formed on the inner rotational part/on the outer rotational sleeve, which projection runs in the longitudinal direction and has recesses in the form of a grid in the longitudinal direction, and the counterstop/the inner stop is injection molded onto this retaining projection. By virtue of the fact that there is an additional retaining projection having recesses in the form of a grid, a reliable connection in the long term of the injection-molded counterstop or of the injection-molded inner stop made of soft material is ensured as a consequence of the form-fitting engagement.
As material for the soft counterstop or for the soft inner stop, use can be made, for example, of thermoplastic polyethylene (PE) or thermoplastic polyurethane (PU). Both the inner rotational part and the outer rotational sleeve are designed as plastic injection-molded parts.
A particularly advantageous refinement is distinguished in that the decrease of the inner diameter (R-R1) and the increase of the outer diameter (R2-R3) of the outer rotational sleeve or of the inner rotational part has a linear profile.
Further embodiments and advantages of the invention are produced by the features also cited in the claims and also by the exemplary embodiments specified below. The features of the claims can be combined with one another in any desired manner insofar as they obviously do not eliminate one another.